Solve for $x$ and $y$ using substitution. ${-5x-4y = -7}$ ${x = -4y+11}$
Since $x$ has already been solved for, substitute $-4y+11$ for $x$ in the first equation. ${-5}{(-4y+11)}{- 4y = -7}$ Simplify and solve for $y$ $20y-55 - 4y = -7$ $16y-55 = -7$ $16y-55{+55} = -7{+55}$ $16y = 48$ $\dfrac{16y}{{16}} = \dfrac{48}{{16}}$ ${y = 3}$ Now that you know ${y = 3}$ , plug it back into $\thinspace {x = -4y+11}\thinspace$ to find $x$ ${x = -4}{(3)}{ + 11}$ $x = -12 + 11$ ${x = -1}$ You can also plug ${y = 3}$ into $\thinspace {-5x-4y = -7}\thinspace$ and get the same answer for $x$ : ${-5x - 4}{(3)}{= -7}$ ${x = -1}$